Generation of redundant scheduled network paths using a branch and merge technique
View Patent ↗A method and apparatus for creating and using multiple redundant paths between endpoints in a scheduled communication network, and for sending copies of data down each path. A path calculation is made for one or more redundant paths between designated branch and merge points in a network using scheduled switch/routers, and duplicate packets are transmitted along each path to the merge point. The first packet received among the configured paths at the merge point is forwarded to a resulting data stream and the later (duplicate) copies from other paths are discarded. Path itineraries are configured to maintain temporal packet sequence in the resulting stream. Path status is monitored and additional paths can be substituted if a path has an outage. Alternatively, multiple divergent paths can be configured, and duplicate packets transmitted along each path, where at least one path delivers data between end points, and a monitoring path also transmits copies of the data to an alternate location. A new routing header may be attached to packets transmitted in the monitoring path, to facilitate conformance with CALEA monitoring requirements.
1. A computer-implemented method comprising:
calculating, by a computer device, a plurality of paths within a data packet network from a branch point to a merge point, wherein a combination of said plurality of paths meets predetermined configuration requirements;
transmitting a copy of each packet received at said branch point along at least two of said plurality of paths;
merging data received from said plurality of paths at said merge point into a single data stream, said merging including monitoring each of said plurality of paths for a predetermined interval for each packet, and forwarding only the first packet of said transmitted copies of said packet to arrive on any of said plurality of paths during said interval;
varying a level of redundancy for selected connections;
wherein said calculating, said transmitting, said merging, and said varying are done on a temporary, per-call basis for Voice Over Internet Protocol (VOIP) data within said data packet network and wherein said calculating, said transmitting, said merging, and said varying are not done on other types of data within said data packet network;
monitoring the status of at least one of said plurality of paths;
determining when said at least one monitored path has experienced an outage;
requesting a calculation of a substitute path meeting said predetermined configuration requirements; and
using said substitute path for transmitting further copies of each packet from said branch point to said merge point.
2. The method of claim 1 in which said data packet network is comprised of one or more scheduled switch/routers (SSR).
3. The method of claim 1 in which segments of said plurality of paths can be used by normal traffic during intervals when no scheduled packets are being transmitted over said segments.
4. The method of claim 1 in which said predetermined configuration requirements include a requirement that at least two of said plurality of paths do not share common communication facilities within said data packet network.
5. The method of claim 1 in which said predetermined configuration requirements include a requirement that the difference between latency times of each of said plurality of paths does not exceed a pre-configured limit, whereby the packets of each path remain in sequence.
6. The method of claim 1 where said predetermined configuration requirements include a requirement for scheduling transmission of said single data stream at a time no earlier than a latency time of the shortest path of said plurality of paths and at a time no later than a latency time of the longest of said plurality of paths, wherein said latency times are calculated between said branch point and said merge point.
7. The method of claim 1 in which at least one of said branch point and said merge point is located within said network.
8. The method of claim 1 in which at least one of said branch point and said merge point is located within a device connected to said data packet network.
9. The method of claim 8 in which said device is a multi-homed device connected to said data packet network at a plurality of access points, and said device is configured to perform a branching function or a merging function or both.
10. The method of claim 1 in which a schedule agent is configured to receive a request for one or more high-reliability data paths, and to calculate said plurality of paths according to topology and latency information known to said schedule agent.
11. The method of claim 1 in which resources for said plurality of paths are released for use by other paths when highly reliable paths are no longer required between said branch point and said merge point.
12. The method of claim 1 wherein said data within said data packet network includes VOIP data and at least one of the group consisting of email, web pages, and file transfers.